The present invention relates to an engine speed control system for a vehicle, and more particularly to a system which starts to control the engine idling speed after an interval when the engine operation is changed from driving condition to idling condition.
Heretofore, a closed loop feedback control system has been provided for controlling the idling speed to a desired idling speed by adjusting the amount of air or the amount of the air-fuel mixture to be induced in the engine in dependency on an error signal which is the difference between a desired reference idling speed and the detected idling speed. The automatic control system stops controlling the idling speed in driving condition which is detected by an idling detecting
The idling detecting system comprises a neutral switch for producing a signal when the gear shift lever of the transmission is in the neutral position, an idling switch which is operated by a throttle lever, and a vehicle speed sensor. The idling detecting system operates to judge the idling operation of the engine from these three signals obtained by the above described switches and sensor for producing an idling signal.
However, since the neutral switch is located in the transmission, the switch is complicated in construction and expensive. Furthermore, when the neutral switch is not activated, the detecting system produces a driving mode signal. Therefore, when the vehicle is started in partial engagement clutch condition, the engine speed is decreased for a short time, because the automatic engine speed control is not affected, which will cause the engine to stop.